The present invention relates to a laser device.
In a solid laser oscillation device, it is conventionally practiced that lamps for excitation, condensing reflectors for the lamps, the electrodes of the lamps, holders for the lamps, a laser rod and so forth are housed in a hermetic container, and cooling water is circulated to prevent the overheating of the lamps and the rod.
FIGS. 5 and 6 are schematic sectional views of a conventional solid laser device. To cool the excitation lamps 14 of the laser device, the electrodes 15 of the lamps are supported by holders 16, and the lamps are located inside the reflection surfaces of condensing reflectors 17 in a hermetic container 18. The excitation lamps 14 are cooled by a circulating liquid 13 such as pure water. The reflection surface of each of the condensing reflectors 17 is constituted by a layer of a plated metal such as silver, gold, chromium and aluminum and high in reflectance, or is constituted by the like. A cooling pipe 11 is provided around a laser medium 12 and divides the interior of the hermetic container 18. The pipe 11 is cooled by a liquid 13' flowing therein. The laser device has a drawback that when the device of the liquid immersion type performs laser oscillation for a long time, the plated metal layer constituting the high in reflectance mirror-like surface of the condensing reflector 17 and develops a trouble such as color change and corrosion to lower the efficiency of the laser oscillation or to make the oscillation impossible in some case. Particularly if the layer is made of plated silver, the device is likely to develop this kind of trouble even if the layer is coated with a protective layer of SiO.sub.2 or the like. The device has another drawback that the purity of the cooling liquid 13 in the hermetic container 18 falls along with the long time use of the device to lower the reflectance of the condensing reflector or cause an extraneous substance to cling to the electrodes of the lamps to change the electric properties of the surface of the electrodes, to make the contact of the electrodes and the holders improper or to break the mutual electric insulation of the electrodes. In consequence, the laser oscillation by the device drops greatly in efficiency or becomes impossible.
The present invention was made in consideration of the drawbacks mentioned above. Accordingly, it is the first object of the invention to provide a laser device of long life.
When the laser device performs the laser oscillation while the temperature of the laser medium 12 is controlled to be 85.degree. C., for example, the liquid 13 having a low temperature of about 15.degree. C. is caused to flow between the condensing reflector 17 and the glass pipe 11 to cool the excitation lamps 14 and the liquid 13' whose temperature is controlled to set the temperature of the laser medium at 85.degree. C. is caused to flow in the glass pipe. In that case, since the liquid 13 for controlling the temperature of the laser medium 12 and the other liquid 13' for cooling the lamps 14 come near each other while being separated from each other only by the glass pipe 11, both the liquids are not sufficiently insulated thermally from each other. For that reason, the temperature of the liquid 13 is affected by that of the other liquid 13' on and near the boundary of them so that the temperature of the former becomes unstable of fluctuates to make the laser oscillation unstable.
The present invention was made in consideration of the latter drawback as well. Accordingly, it is the second object of the invention to keep the temperature of a laser medium constant to stabilize laser oscillation.